Any single-branch charging and discharging control method under multi-branch battery parallel connection

Abstract

The invention discloses a charging and discharging control method for any single branch under parallel connection of multi-branch batteries, which comprises a driving mode and a charging mode, and is characterized in that in the driving mode, the electric quantity of each branch is gradually discharged from high to low, so that the electric quantity of all branches can be used up; in the charging mode, each branch is charged gradually from low to high, so that all branches can be fully charged. According to the invention, various series-parallel flexible combinations can be realized, the electric quantity between the branches can be automatically balanced, independent charging and discharging of a single branch can be realized, each branch can be fully charged, and each branch can be discharged; and the power consumption is maximized.

Description

Technical Field

[0001] The present invention belongs to the technical field of battery charging and discharging, and in particular relates to a method for controlling charging and discharging of any single branch of multi-branch batteries in parallel. Background Art

[0002] With the continuous development and popularization of new energy vehicles, batteries, as the core components of new energy vehicles, have also been continuously improved and upgraded; for example, in order to extend the driving time, multiple branches are usually connected in series and parallel to increase the overall battery capacity;

[0003] At present, conventional battery multiple branches are connected in series and parallel. Generally, the battery power of each branch will deviate, which will produce a bucket effect. The battery with the lowest power will serve as the lower limit of the vehicle's power. In addition, during driving, when one of the branches fails, it will cause the entire vehicle's battery to fail, and other batteries cannot be used, affecting the overall battery life. Summary of the invention

[0004] In order to solve the defects and shortcomings in the above-mentioned prior art, the present invention provides a method for controlling the charging and discharging of any single branch under multi-branch batteries in parallel, which can realize various flexible series-parallel combinations, automatically balance the power between branches, and independently charge and discharge a single branch, fully charge each branch, and fully discharge each branch; maximize the use of power, and when a branch battery fails, only cut off the faulty branch, and other branches can support the vehicle to continue driving, thereby greatly reducing the rescue risk.

[0005] To achieve the above object, the present invention provides the following technical solution: a method for controlling the charging and discharging of any single branch of a multi-branch battery in parallel, including two modes: a driving mode and a charging mode.

[0006] The specific steps of driving mode are as follows:

[0007] A1. After the battery replacement is completed, if there is no fault in the branch where the slave control is located, the slave control with higher total pressure will be attracted first, and then the slave control with lower total pressure will be attracted;

[0008] A2. During driving, if the driving current drops to within the specified current value, and the pressure difference between the un-energized branch and the energized branch is less than the specified pressure difference value, and lasts for a specified time, the slave control relay with a total low pressure will be energized;

[0009] A3. Alarm from the branch where the slave control is located: when the driving current drops to within the specified current value and exceeds the specified time, the faulty branch is forcibly disconnected, and other branches are not affected;

[0010] A4. Insert the charging gun, switch from driving to charging, and the BMS will forcefully request high voltage. After the VCU sends the high voltage command, the main negative relay will be disconnected, and all branch relays will be disconnected. When the driving is switched to charging, the main circuit will be forced to disconnect.

[0011] The specific steps of the charging mode are as follows:

[0012] B1. After inserting the charging gun and entering the charging mode, if there is no fault in the branch where the slave control is located, the slave control with low total pressure will be attracted first, and then the slave control with high total pressure will be attracted;

[0013] B2. During the charging process, if the voltage difference between the un-energized branch and the energized branch is less than the specified voltage difference, the requested current is reduced to the specified current or the minimum output current allowed by the charging pile; after the current is reduced, wait for the branch voltage difference to be within the specified voltage difference, and energize the slave control with the lower total voltage;

[0014] B3. Charging is completed, the current is requested to be reduced to the specified current or the minimum output current allowed by the charging pile, and the branch with high single-cell voltage is disconnected;

[0015] B4. Continue charging until all branches are charged, disconnect the fast charging relay, and the BMS forces a high voltage request. After waiting for the VCU to send a high voltage command, the main negative relay is disconnected, and then the remaining branch relay is disconnected. If charging is completed / charging is abnormal, the high voltage will be forced to be lowered.

[0016] Preferably, in the step A1, the slave controller with low total voltage is attracted, and its voltage difference with the highest branch total voltage is within 5V.

[0017] Preferably, in step A2, if the driving current is reduced to a specified current of 10A, the voltage difference between the un-energized branch and the energized branch is less than a specified voltage difference of 5V, and lasts for a specified time of 5S.

[0018] Preferably, in step A3, the driving current is reduced to a specified current of 10A, and the specified timeout period is 60S.

[0019] Preferably, the charging in step A4 requires closing the slave control relay of the total voltage low branch.

[0020] Preferably, in step B1, the slave controller with a higher total pressure is attracted, and its voltage difference with the lowest branch total voltage is within 5V.

[0021] Preferably, in step B2, the voltage difference between the un-energized branch and the energized branch is less than a specified voltage difference of 5V, the requested current is reduced to a specified current of 5A, and the branch voltage difference is waited to be at a specified voltage difference of 5V.

[0022] Preferably, in step B3, the requested current is reduced to a specified current of 5A.

[0023] Preferably, in step B4, until all branches are fully charged, when the single cell voltage meets the condition, only one branch relay is energized.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention can realize various flexible series and parallel combinations, can automatically balance the power between the branches, and can independently charge and discharge a single branch. It can fully charge each branch and also fully discharge each branch. It maximizes the use of power, and when a battery in a branch fails, only the faulty branch is cut off, and other branches can support the vehicle to continue driving, greatly reducing the rescue risk. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of embodiment 2 of the present invention. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] Example 1

[0029] A method for controlling the charging and discharging of any single branch of a multi-branch battery in parallel, including two modes: a driving mode and a charging mode.

[0030] Driving mode:

[0031] 1. After the battery replacement is completed, if there is no fault in the branch where the slave control is located, the slave control with a higher total voltage will be energized first, and then the slave control with a lower total voltage (with a voltage difference of less than 5V from the highest branch total voltage) will be energized.

[0032] 2. During driving, if

[0033] Driving current is reduced to less than 10A

[0034] The voltage difference between the un-energized branch and the energized branch is less than 5V

[0035] Lasts 5 seconds

[0036] Then the slave control relay with low total voltage will be attracted.

[0037] 3. Alarm from the branch where the slave is located:

[0038] Driving current is reduced to less than 10A

[0039] Timeout 60s

[0040] Force disconnection of faulty branch. Other branches are not affected.

[0041] 4. Insert the charging gun, switch from driving to charging, and the BMS will forcefully request the high voltage. After the VCU sends the high voltage command, the main negative relay is disconnected, and then all branch relays are disconnected. (Charging requires the slave control relay of the total low voltage branch to be energized). When driving is switched to charging, the main circuit will be forced to disconnect.

[0042] Charging Mode:

[0043] 1. After inserting the charging gun and entering the charging mode, if there is no fault in the branch where the slave control is located, the slave control with low total voltage will be attracted first, and then the slave control with high total voltage (the voltage difference with the lowest branch total voltage is within 5V) will be attracted.

[0044] 2. During the charging process, if the voltage difference between the un-engaged branch and the engaged branch is less than 2V, reduce the requested current to 5A (or the minimum output current allowed by the charging pile). After the current is reduced, wait for the branch voltage difference to be within 5V and engage the slave control with a low total voltage.

[0045] 3. After charging is completed, the request current is reduced to 5A (or the minimum output current allowed by the charging pile), and the branch with high single-cell voltage is disconnected.

[0046] 4. Continue charging until all branches are fully charged (single-cell voltage meets the conditions, and only one branch relay is energized at this time). Disconnect the fast charge relay. BMS forces a request for high voltage. Wait for VCU to issue a high voltage command, and after the main negative relay is disconnected, disconnect the remaining branch relay. If charging is completed / charging is abnormal, high voltage will be forced to be lowered.

[0047] Example 2

[0048] like Figure 1 As shown, this embodiment adopts 2 series and 6 parallels, 12 boxes of batteries, first 2 boxes are connected in series, then 2 boxes of series branches are connected in parallel, and then 3 branches are connected in parallel. The battery designed in this embodiment has a single box battery of 320v and a system voltage of 640V, which is a high-voltage system and is convenient for reducing the charging and discharging current.

[0049] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for controlling the charge and discharge of any single branch of multi-branch batteries in parallel, characterized in that: It includes two modes: driving mode and charging mode. The specific steps of driving mode are as follows: A1. After the battery replacement is completed, if there is no fault in the branch where the slave control is located, the slave control with high total pressure will be attracted first, and then the slave control with low total pressure will be attracted; A2. During driving, if the driving current drops to within the specified current value, and the pressure difference between the un-energized branch and the energized branch is less than the specified pressure difference value, and lasts for a specified time, the slave control relay with a total low pressure will be energized; A3. Alarm from the branch where the slave control is located: when the driving current drops to within the specified current value and exceeds the specified time, the faulty branch is forcibly disconnected, and other branches are not affected; A4. Insert the charging gun, switch from driving to charging, and the BMS will forcefully request high voltage. After the VCU sends the high voltage command, the main negative relay will be disconnected, and all branch relays will be disconnected. When the driving is switched to charging, the main circuit will be forced to disconnect. The specific steps of the charging mode are as follows: B1. After inserting the charging gun and entering the charging mode, if there is no fault in the branch where the slave control is located, the slave control with low total pressure will be attracted first, and then the slave control with high total pressure will be attracted; B2. During the charging process, if the voltage difference between the un-energized branch and the energized branch is less than the specified voltage difference, the requested current is reduced to the specified current or the minimum output current allowed by the charging pile; After the current is reduced, wait for the branch pressure difference to be within the specified pressure difference, and then attract the slave control with low total pressure; B3. Charging is completed, the current is requested to be reduced to the specified current or the minimum output current allowed by the charging pile, and the branch with high single-cell voltage is disconnected; B4. Continue charging until all branches are charged, disconnect the fast charging relay, and the BMS forces a high voltage request. After waiting for the VCU to send a high voltage command, the main negative relay is disconnected, and then the remaining branch relay is disconnected. If charging is completed / charging is abnormal, the high voltage will be forced to be lowered.

2. The method for controlling charging and discharging of any single branch of multi-branch batteries in parallel according to claim 1, characterized in that: In the step A1, the slave controller with low total voltage is attracted, and the voltage difference between it and the highest branch total voltage is within 5V.

3. The method for controlling charging and discharging of any single branch of multi-branch batteries in parallel according to claim 1, characterized in that: In step A2, if the running current is reduced to a specified current of 10A, the voltage difference between the un-energized branch and the energized branch is less than a specified voltage difference of 5V, and lasts for a specified time of 5S.

4. The method for controlling charging and discharging of any single branch of multi-branch batteries in parallel according to claim 1, characterized in that: In step A3, the driving current is reduced to a specified current of 10A, and the specified timeout period is 60S.

5. The method for controlling charging and discharging of any single branch of multi-branch batteries in parallel according to claim 1, characterized in that: In the step A4, the charging needs to attract the slave control relay of the total voltage low branch.

6. The method for controlling charging and discharging of any single branch of multi-branch batteries in parallel according to claim 1, characterized in that: In the step B1, the slave controller with the higher total voltage is attracted, and the voltage difference between the slave controller and the lowest branch total voltage is within 5V.

7. The method for controlling charging and discharging of any single branch of multi-branch batteries in parallel according to claim 1, characterized in that: In the step B2, the voltage difference between the un-attracted branch and the attracted branch is less than the specified voltage difference of 5V, the requested current is reduced to the specified current of 5A, and the branch voltage difference is waited to be at the specified voltage difference of 5V.

8. The method for controlling charging and discharging of any single branch of multi-branch batteries in parallel according to claim 1, characterized in that: In step B3, the requested current is reduced to a specified current of 5A.

9. The method for controlling charging and discharging of any single branch of multi-branch batteries in parallel according to claim 1, characterized in that: In step B4, until all branches are fully charged, when the single cell voltage meets the condition, only one branch relay is energized.

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